SVI’s Leak Detector Time Delay Relay / TDR #  BP-4170-FSD helps eliminate thermal line contraction in service station pumps located where the temperatures dip into the chilly range. Leak detectors, which delay the product flow for two seconds, have some problems. When the air temperature is colder than the temperature inside the tank diaphragm style leak detectors do not stay primed. Pressure is not maintained in the lines from the submersible pump. Consequently, a two second delay is not long enough for the fuel to return and the leak detector misinterprets low pressure as a leak and slows the product flow. The BP-4170-FSD, which delays the product flow, solves most of these problems. SVI is your answer!